#include <reg52.h>
#define uchar unsigned char
#define uint unsigned int 
sbit led1=P1^0;
uchar num;
void main()
{
  TMOD=0x01;
	TH0=(65536-45872)/256;
	TL0=(65536-45872)%256;
	EA=1;
	ET0=1;
	TR0=1;
	while(1);
}
void T0_time() interrupt 1
{
  TH0=(65536-45872)/256;
	TL0=(65536-45872)%256;
	num++;
	if(20==num)
	{
	  num=0;
		led1=~led1;
	}	
}
